1. Field of the Invention
This invention relates generally to safety devices for mowing equipment, and more particularly to a safety blocker attached to the edge portion of the mower deck of a rotary mower to prevent inadvertent starting of the mower's engine during blade changing and manual debris removal from within the deck during which the blades are hand-rotated.
2. Description of Related Art
During mowing operation with a rotary-type gasoline powered lawn mower, encountering heavy debris can damage or substantially dull the blade edges to the point where the mowing operations become ineffective. Because of the simplicity of a rotary-type mower, the mower blades are relatively easily changed during mowing operations by the removal of one or more blade mounting bolts from the engine output shaft within the deck area of the mower.
If the engine is sufficiently heated from mowing operations and has not had sufficient time to cool, the rotation of the blades which occurs during the removal of the blade mounting bolts can be sufficient to pass the piston through a compression stroke. Because of the heat build-up in the engine itself, although the spark plug ignition has been electrically interrupted, the engine may still fire.
Because this dangerous problem is well known, many rotary mower users faced with such a blade change during mowing operations must first find a means for blocking the movement of the blade which is typically done by wedging a block of wood or metal between one of the blades and the inside surface of the deck. Thereafter, conventional hand tools may be used to remove the blade, either sharpen or replace it, reinstall the attaching bolts and continue the mowing operation.
As well known as this procedure is to those using a rotary type mower, the danger still exists that the wedge of wood or metal can become dislodged, allowing the blade to rotate sufficiently to pass the piston through a compression stroke causing firing of the engine and serious harm to the hands and forearms of the user.
It is also well known that rotary-type lawn mowers are prone to collection of mown debris within the deck of the mower. When sufficiently accumulated, this debris buildup will inhibit proper mowing and mown grass discharge from the deck by the elongated rotating blade positioned centrally therewithin. This is particularly problematic when the grass being mowed is somewhat damp or water laden which tends to enhance the clinging ability of the grass being mowed along with other debris within the grass.
A most common prior art means for removal of this debris is simply to tip one side of the deck up and manually remove it by hand or with a hand tool or other hand implement sufficiently strong to scrape accumulated debris away from inner surfaces of the deck. To accomplish debris removal in this fashion, the blade is typically randomly shifted or rotated on the shaft of the engine to get at all of the debris within the deck.
An automatic cleaning device intended for debris removal from the under deck of rotary mowers is disclosed in U.S. Pat. No. 2,992,524 invented by Stabnau providing means for introducing water into the interior of the deck or housing from a conventional household water source and during a period of engine operation. The rotating blade thus forces the water against the debris to effect a flushing action without having to manually removing the debris.
Zipf, in U.S. Pat. No. 2,523,640 teaches a guard for a mowing machine which prevents injury during mowing operation.
In U.S. Pat. No. 3,084,494, Joslin teaches a safety device for mowers which includes an openable access door having a resilient steel wire mounted thereon which will impinge upon a rotating blade as the safety door is opened for inspection and cleaning of the deck area thus providing an audible warning that the rotating blades have not yet stopped.
The present invention provides an economical, easily installable rotary blade blocker which, when releasably attached to the edge portion of the mower deck, will prevent rotation of the blade sufficient to cause the engine of the mower to inadvertently start. Moreover, should a firing of the engine occur, there will be insufficient power and momentum developed to dislodge the blade blocker from its clamping engagement to the deck thus protecting the operator from injury while replacing mower blades or manually cleaning accumulated debris from within the deck and around the blade of the mower.